[lld] r343667 - [LLD] - Do not crash when reporting errors when .debug_line_str (DWARF5) is used

George Rimar via llvm-commits llvm-commits at lists.llvm.org
Wed Oct 3 01:59:46 PDT 2018


Author: grimar
Date: Wed Oct  3 01:59:46 2018
New Revision: 343667

URL: http://llvm.org/viewvc/llvm-project?rev=343667&view=rev
Log:
[LLD] - Do not crash when reporting errors when .debug_line_str (DWARF5) is used

Imagine we have the following code:

int foo();
int main() { return foo(); }

It will crash if you try to compile it with
`clang -O0 -gdwarf-5 test.cpp -o test -g -fuse-ld=lld`

The crash happens inside the LLVM DWARF parser because LLD does not provide
the .debug_line_str section. At the same time for correct parsing and reporting,
we anyways need to provide this section from our side.

The patch fixes the issue.


Added:
    lld/trunk/test/ELF/debug-line-str.s
Modified:
    lld/trunk/ELF/DWARF.cpp
    lld/trunk/ELF/DWARF.h

Modified: lld/trunk/ELF/DWARF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/DWARF.cpp?rev=343667&r1=343666&r2=343667&view=diff
==============================================================================
--- lld/trunk/ELF/DWARF.cpp (original)
+++ lld/trunk/ELF/DWARF.cpp Wed Oct  3 01:59:46 2018
@@ -48,6 +48,8 @@ template <class ELFT> LLDDwarfObj<ELFT>:
       GnuPubTypesSection = toStringRef(Sec->Data);
     else if (Sec->Name == ".debug_str")
       StrSection = toStringRef(Sec->Data);
+    if (Sec->Name == ".debug_line_str")
+      LineStringSection = toStringRef(Sec->Data);
   }
 }
 

Modified: lld/trunk/ELF/DWARF.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/DWARF.h?rev=343667&r1=343666&r2=343667&view=diff
==============================================================================
--- lld/trunk/ELF/DWARF.h (original)
+++ lld/trunk/ELF/DWARF.h Wed Oct  3 01:59:46 2018
@@ -42,6 +42,7 @@ public:
   StringRef getFileName() const override { return ""; }
   StringRef getAbbrevSection() const override { return AbbrevSection; }
   StringRef getStringSection() const override { return StrSection; }
+  StringRef getLineStringSection() const override { return LineStringSection; }
 
   StringRef getGnuPubNamesSection() const override {
     return GnuPubNamesSection;
@@ -72,6 +73,7 @@ private:
   StringRef GnuPubNamesSection;
   StringRef GnuPubTypesSection;
   StringRef StrSection;
+  StringRef LineStringSection;
 };
 
 } // namespace elf

Added: lld/trunk/test/ELF/debug-line-str.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/debug-line-str.s?rev=343667&view=auto
==============================================================================
--- lld/trunk/test/ELF/debug-line-str.s (added)
+++ lld/trunk/test/ELF/debug-line-str.s Wed Oct  3 01:59:46 2018
@@ -0,0 +1,136 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux -dwarf-version=5 %s -o %t.o
+# RUN: not ld.lld %t.o -o %t1 2>&1 | FileCheck %s
+
+# Check we do not crash and able to report the source location.
+
+# CHECK:      error: undefined symbol: foo()
+# CHECK-NEXT: >>> referenced by test.cpp:3
+# CHECK-NEXT: >>>               {{.*}}.o:(.text+0x1)
+
+# The code below is the reduced version of the output
+# from the following invocation and source:
+#
+# // test.cpp:
+# int foo();
+# int main() {
+#   return foo();
+# }
+#
+# clang -gdwarf-5 test.cpp -o test.s -S
+# clang version 8.0.0 (trunk 343487)
+
+.text
+.file "test.cpp"
+.globl main
+.type main, at function
+main:
+.Lfunc_begin0:
+ .file 0 "/home/path" "test.cpp" md5 0x8ed32099ab837bd13543fd3e8102739f
+ .file 1 "test.cpp" md5 0x8ed32099ab837bd13543fd3e8102739f
+ .loc 1 3 10 prologue_end
+ jmp _Z3foov
+.Lfunc_end0:
+
+.Lstr_offsets_base0:
+.section .debug_str,"MS", at progbits,1
+ .asciz "stub"
+
+.section .debug_str_offsets,"", at progbits
+ .long 0
+
+.section .debug_abbrev,"", at progbits
+ .byte 1                           # Abbreviation Code
+ .byte 17                          # DW_TAG_compile_unit
+ .byte 0                           # DW_CHILDREN_yes
+ .byte 37                          # DW_AT_producer
+ .byte 37                          # DW_FORM_strx1
+ .byte 19                          # DW_AT_language
+ .byte 5                           # DW_FORM_data2
+ .byte 3                           # DW_AT_name
+ .byte 37                          # DW_FORM_strx1
+ .byte 114                         # DW_AT_str_offsets_base
+ .byte 23                          # DW_FORM_sec_offset
+ .byte 16                          # DW_AT_stmt_list
+ .byte 23                          # DW_FORM_sec_offset
+ .byte 27                          # DW_AT_comp_dir
+ .byte 37                          # DW_FORM_strx1
+ .byte 17                          # DW_AT_low_pc
+ .byte 1                           # DW_FORM_addr
+ .byte 18                          # DW_AT_high_pc
+ .byte 6                           # DW_FORM_data4
+ .byte 0                           # EOM(1)
+ .byte 0                           # EOM(2)
+
+ .byte 2                           # Abbreviation Code
+ .byte 46                          # DW_TAG_subprogram
+ .byte 0                           # DW_CHILDREN_no
+ .byte 17                          # DW_AT_low_pc
+ .byte 1                           # DW_FORM_addr
+ .byte 18                          # DW_AT_high_pc
+ .byte 6                           # DW_FORM_data4
+ .byte 64                          # DW_AT_frame_base
+ .byte 24                          # DW_FORM_exprloc
+ .byte 3                           # DW_AT_name
+ .byte 37                          # DW_FORM_strx1
+ .byte 58                          # DW_AT_decl_file
+ .byte 11                          # DW_FORM_data1
+ .byte 59                          # DW_AT_decl_line
+ .byte 11                          # DW_FORM_data1
+ .byte 73                          # DW_AT_type
+ .byte 19                          # DW_FORM_ref4
+ .byte 63                          # DW_AT_external
+ .byte 25                          # DW_FORM_flag_present
+ .byte 0                           # EOM(1)
+ .byte 0                           # EOM(2)
+
+ .byte 3                           # Abbreviation Code
+ .byte 36                          # DW_TAG_base_type
+ .byte 0                           # DW_CHILDREN_no
+ .byte 3                           # DW_AT_name
+ .byte 37                          # DW_FORM_strx1
+ .byte 62                          # DW_AT_encoding
+ .byte 11                          # DW_FORM_data1
+ .byte 11                          # DW_AT_byte_size
+ .byte 11                          # DW_FORM_data1
+ .byte 0                           # EOM(1)
+ .byte 0                           # EOM(2)
+ .byte 0                           # EOM(3)
+
+.section .debug_info,"", at progbits
+.Lcu_begin0:
+ .long 61                         # Length of Unit
+ .short 5                         # DWARF version number
+ .byte  1                         # DWARF Unit Type
+ .byte  8                         # Address Size (in bytes)
+ .long  .debug_abbrev             # Offset Into Abbrev. Section
+
+ .byte  1                         # Abbrev [1] 0xc:0x35 DW_TAG_compile_unit
+ .byte  0                         # DW_AT_producer
+ .short 0                         # DW_AT_language
+ .byte  0                         # DW_AT_name
+ .long  .Lstr_offsets_base0       # DW_AT_str_offsets_base
+ .long  .Lline_table_start0       # DW_AT_stmt_list
+ .byte  0                         # DW_AT_comp_dir
+ .quad  .Lfunc_begin0             # DW_AT_low_pc
+ .long  .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ 
+ .byte  2                         # Abbrev [2] 0x26:0x16 DW_TAG_subprogram
+ .quad  .Lfunc_begin0             # DW_AT_low_pc
+ .long  .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ .byte  1                         # DW_AT_frame_base
+ .byte  87
+ .byte  0                         # DW_AT_name
+ .byte  1                         # DW_AT_decl_file
+ .byte  2                         # DW_AT_decl_line
+ .long  60                        # DW_AT_type
+                                  # DW_AT_external
+
+ .byte  3                         # Abbrev [3] 0x3c:0x4 DW_TAG_base_type
+ .byte  0                         # DW_AT_name
+ .byte  5                         # DW_AT_encoding
+ .byte  4                         # DW_AT_byte_size
+ .byte  0                         # End Of Children Mark
+
+.section .debug_line,"", at progbits
+.Lline_table_start0:




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